[pkg] Use io.open with utf-8 encoding to read long description from README This forces decoding so that this is consistent between Python 2 and 3 as, in Python 3, decoding which would occur anyways and may fail depending on the environment locale settings.

[dataimport] order of ExtEntities should be irrelevant (closes #13117472)

Test and fix "pickleability" of Binary objects which has been recently broken while some cubes rely on this (eg fastimport). Do some licensing/pep8 cleanup along the way. Closes #13385274